872 MRS. E. W. SEXTON ON AMPHIPODA [NoV. 23, 



Eyes large and prominent, and pyiiform in the adnlt, with 

 numerous small dark ommatidia. In the young the eyes are 

 round ; in one specimen, 4 mm., the very dark ommatidia 

 numbered 22, arranged in 5 rows ; in another, 8 mm., the shape 

 was a rounded oval, the ommatidia numbering about 80. 



Antennce : si(,perior anteiuia, full-grown female. — 1st joint of 

 the peduncle not so long as the 2nd and 3rd together ; 3rcl nearly 

 two-thirds the length of the 2nd ; 1st and 2nd with apical teeth. 

 Primary flagellum scarcely as long as the peduncle, each joint 

 carrying a calceolus and a long sensory filament ; 12- jointed in 

 the largest specimens, 12"5 mm. long, with all 7 peraeon-humps 

 well developed, as in fig. 49, In slightly smaller specimens, 

 11 mm., with the 4th and 5th segment humps minute, the joints 

 of the flagellum numbered 11, while in the smallest 'Huxley' 

 sj^ecimen, 10 mm., there were only 10 joints in each flagellum. 

 The accessory flagellum consists of 1 small joint with 1 long ciliated 

 hair and 1 sensory cleft seta (fig. 52) ; the ciliated liair being inset 

 on the under side, much lower than the seta, gives the appearance, 

 when in position, of a minute apical joint. 



Male. ' Huxley' specimen, 8"75 mm.— 1st joint as long as the 

 2nd and 3rd together ; 3rd not quite half the length of the 2nd. 

 Frhnary flagellum 2 3- jointed ; accessory flagellum as in female, 

 tipped with long ciliated hair and 2 cleft setae. The 1st joint of 

 the primary flagellum is long and broad ; the 2nd short ; the 

 following 8 successively a little longer and thinner, each with a 

 calceolus and a dense group of sensory filaments (fig. 61) on the 

 inner side ; the next 4 joints are alternately long and short, the 

 long ones with a cluster of setae only, the short ones with a 

 calceolus and sensory filaments. This alternation of long and 

 short joints occurs also in the inferior antenna (cf . also Eusirus 

 hiscayensis). The remaining 9 joints are of equal length, with 

 clusters of small filaments. The ciliated hairs on the peduncle 

 are remai-kable for the great length of the " feathering." 



In the Irish specimens, 10 ram., the 1st joint of the peduncle 

 is shorter than the 2nd and 3rd combined ; 3rd joint about half 

 the length of the 2nd. The primary flagella are all broken, 

 31 joints remaining on one. 



The young in the incubatory pouch has the 1st and 2nd joints 

 subequal in length, the 3rd half as long as the 2nd ; primary 

 flagellum of 4 joints not nearly so long as the peduncle ; accessory 

 flagellum (fig. 53) 1 -jointed, tipped with 2 setae and 1 sensory 

 filament. 



Inferior antenna. Fvill-grown female. — Agi-ees with Sars' 

 description. 



Male. 'Huxley' specimen. — 4th joint of the peduncle broader 

 and slightly shorter than the 5th ; 3rd, 4th, and 5th posteriorly 

 laminar. The flagellum subequal to the peduncle in length, 24- 

 jointed ; the first 4 joints each cany a calceolus and a cluster of 

 long setfe ; the next 8 are alternately long and short, the shoi't 

 ones with a calceolus and long setae; the 14th, 17th, 20th, and 



